Laminating machines ordinarily can operate on one of two types of laminating material. Machines designed for a high throughput are provided with continuous rolls of laminating film and an upper and lower web are brought together with the material to be laminated between the webs and the webs are heated and then squeezed together under pressure to produce the laminated article. It is obvious that such machines are not well adapted for use when only one or a few articles are to be laminated. Thus, such machines find their primary application among relatively large industrial users and are not suitable for use in small offices, libraries or the like.
A second type of machine is primarily adapted for use with prefabricated laminating packets which consist of two laminating sheets held together at one end. Such prefabricated laminating packets which make use of a tear-off tab are described and claimed in copending application Ser. No. 784,668 filed Apr. 5, 1977, now U.S. Pat. No. 4,185,405. Such machines are well adapted for short runs or even a single operation but are not well suited for long runs. Also such machines typically utilize a folded carrier for handling and also for isolating the packets from the machine heating elements. Such carriers prevent scratching of the laminate and leak through of melted adhesive.
The laminating sheets themselves (whether in the form of continuous webs or packets) ordinarily consist of a pair of plastic sheets and ordinarily one of the sheets is transparent (at least after the lamination operation) and usually both sheets would be transparent. At least one of the sheets must have a heat-activated adhesive or a thermoplastic coating facing the opposite sheet and normally both sheets are so constituted. The sheets are preferably of Mylar film coated with a thin layer of a thermoplastic material such as a polyolefin, suitably polyethylene.